cross-post

[Usenet; very common] To post a single
article simultaneously to several newsgroups. Distinguished from
posting the article repeatedly, once to each newsgroup, which
causes people to see it multiple times (which is very bad form).
Gratuitous cross-posting without a Followup-To line directing
responses to a single followup group is frowned upon, as it tends
to cause followup articles to go to inappropriate newsgroups
when people respond to various parts of the original posting.